The FAPY-DNA glycosylase (Fpg) is required for survival of the cyanobacterium Synechococcus elongatus under high light irradiance

The gene for the DNA repair enzyme Fpg from Synechococcus elongatus was det ected immediately downstream of the photosystem I gene psaE. fpg is likely expressed together with psaE by transcriptional readover while psaE is most ly expressed independently. Segregated psaE and fpg deletion strains were o btained upon insertional inactivation of both genes in S. elongatus. These mutants are viable under photoautotrophic conditions, but fail to grow unde r high light regimes that likely cause oxidative stress. These high light s ensitive phenotypes suggest that the Fpg protein, which has been shown to r epair DNA lesions caused by reactive oxygen species in Escherichia coli, ma y be involved in the photoprotection of cyanobacteria against oxidative dam age caused under high irradiance. (C) 2000 Federation of European Microbiol ogical Societies. Published by Elsevier Science B.V. All rights reserved.